Combustion system including at least one fuel flow equalizer

ABSTRACT

Embodiments disclosed herein are directed to a combustion system including at least one fuel flow equalizer for reducing fuel flow velocity distribution and improving flame stabilization within a combustion space. Additionally, a charged flame anchoring apparatus may be positioned above the at least one fuel flow equalizer for attaching the flame thereto and improving flame stability.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 61/764,267 filed 13 Feb. 2013, which, to the extent not inconsistentwith the disclosure herein, is incorporated by reference.

BACKGROUND

Fuel injection at high speed into a combustion zone may contribute to orcause instabilities in flame position and shape of a flame. High fuelinjection speeds can result in non-uniform fuel distribution andunstable flame propagation within the combustion space, which can causesuch problems such as poor combustion, increased emissions ofpollutants, flashback, poor heat transfer, reduced component life, andpotential system damages among others.

Flame stabilization can be required in combustion systems to prevent acombustion flame front from moving upstream from a desired combustionzone toward a source of introduced fuel, causing a flashback that candamage structures within the fuel-air mixing region of the combustionsystem. Flame stabilization can also be dependent upon the speed atwhich the fuel-air mixture enters the combustion zone where propagationof the flame can be desired. A sufficiently low velocity can be retainedin the region where the flame can be desired in order to sustain theflame. A region of low velocity can be achieved by causing recirculationof a portion of the fuel-air mixture already burned, thereby providing asource of ignition to the fuel-air mixture entering the combustion zone.However, the fuel-air mixture flow pattern, including any recirculation,is one important factor to achieving flame stability.

Flame stability can be achieved by placement of a bluff body in the flowpath of a fuel-air mixture within a combustion zone. A bluff bodytypically defines a leading edge and a trailing edge, and separation ofa mixture passing over the bluff body occurs at the trailing edge of thebluff body thereby forming a wake downstream of the trailing edge. Thevelocity of the fuel-air mixture in the wake region can be much lowerthan the velocity of the fuel-air mixture flowing in the main streamaround the bluff body thereby supporting recirculation. One problemassociated with using a bluff body can be that the flame can be anchoredto the bluff body and the excessive heat can be life-limiting.

One approach for promoting a stable flame in a combustion system topromote low emissions, can be placement of a swirler downstream, butthis approach has been disadvantageous in that a flashback event, suchas from a flow disturbance, can destroy the swirler. Also, adequatemixing downstream of a swirler can be difficult to achieve.

Furthermore, methods for stabilizing flames can include using chargedanchoring apparatuses for attaching flames and better controlling theirposition and shape. Although these apparatuses can be favorable forflame stabilization, subsonic and/or supersonic speeds of fuel flowbeing injected into combustion volumes can make flame control moredifficult, especially when attempting to stabilize flames at very highBTU levels.

SUMMARY

Embodiments disclosed herein are directed to various combustion systemsconfigured for fuel flow equalization and stabilization of a flame in acombustion space. In an embodiment, a combustion system includes atleast one burner nozzle, a fuel flow equalizer, at least one flameanchoring apparatus, and a voltage power supply. The at least one burnernozzle is configured to discharge fuel into a combustion space sized andconfigured to at least partially contain a flame produced duringcombustion of the fuel and an oxidizer (e.g., air). The at least onefuel flow equalizer is positioned downstream from the at least oneburner nozzle, and includes a plurality of openings sized and configuredto allow the fuel to pass therethrough. The flame anchoring apparatus ispositioned downstream from the at least one fuel flow equalizer. Thevoltage power supply is electrically coupled to the flame anchoringapparatus. The voltage power supply is configured to bias the flameanchoring apparatus so that the flame is attracted to the flameanchoring apparatus.

In an embodiment, a method for stabilizing a flame within a combustionspace is disclosed. A stream including fuel is discharged from at leastone nozzle into a combustion space. The fuel is passed through at leastone fuel flow equalizer structure positioned downstream from the atleast one nozzle. The fuel and an oxidizer (e.g., air) is ignited toproduce a flame. An electrical potential is applied to a flame anchoringapparatus effective to anchor the flame to the flame anchoringapparatus.

Features from any of the disclosed embodiments may be used incombination with one another, without limitation. In addition, otherfeatures and advantages of the present disclosure will become apparentto those of ordinary skill in the art through consideration of thefollowing detailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a velocity distribution of fuel and a respectiveshape of a flame within a combustion space, according to an example.

FIG. 1B illustrates the behavior of a flame according to fuel flowvelocity distribution, according to an example.

FIGS. 2A and 2B illustrate a velocity distribution of fuel and arespective shape of a flame within a combustion space employing a fuelflow equalizer disposed between a fuel nozzle and a flame, according toembodiments.

FIGS. 3A-3F illustrate different shapes and patterns for fuel flowequalizer, according to embodiments.

FIG. 4 illustrates a combustion system including any of the fuel flowequalizers disclosed herein and a flame anchoring apparatus, accordingto an embodiment.

DETAILED DESCRIPTION

Embodiments disclosed herein are directed to various combustion systemsconfigured for fuel flow equalization and stabilization of a flame in acombustion space. As used herein, a “fuel flow equalizer” refers to adevice that can be employed for spreading and/or substantiallyequalizing a combustible fuel and/or fuel mixture and reducing speed ofthe combustible fuel and/or fuel mixture for a combustion reaction in amanner that may improve flame stability. As used herein, “flamestability” refers to a capability of a flame being supported withoutblowing out, which can be achieved when fuel flow velocity and flamespeed are approximately equal. As used herein, an “anchoring apparatus”refers to an electrically conducting device located at least proximateto a flame and configured for coupling the flame thereto in a mannerthat may improve flame stability.

According to various embodiments disclosed herein, a combustion systemmay include a fuel flow equalizer may also promote rapid mixing offuel/air flow streams for complete fuel combustion within the combustionspace. The fuel flow equalizer may be arranged in the path of fuel flowand can include any number of suitable materials such as metallicmaterials, which may be capable of withstanding high pressures andtemperatures. The fuel flow equalizer may exhibit various geometricconfigurations having, different shapes and patterns that may provideincreased flame stability and spread or equalize velocity of the fuelflow in a high area near and/or in the combustion zone. Different shapesof the fuel flow equalizer can include square, circular, andrectangular, among others, while the different patterns can includehoneycomb patterns, cylindrical patterns, and other mesh patterns.

The fuel flow equalizer may also include a plurality of fuel flow pathsdepending on the combustion system, with each path being defined by meanhydraulic diameter and spatial orientation of the opening in the fuelflow equalizer, and take into account the fuel and fuel/air ratio. Theconfiguration of this embodiment may produce a shaped flame that maymove outward from the middle when its equivalent ratio may increase andmay become very tight, positioning the flame away from the fuel flowequalizer, achieving stable combustion with very low emissions (NOx, CO,and HC) and nonexistent large-scale acoustics. Additionally, the maximumvelocity of fuel-air flow may be reduced immediately after the nozzleand uniformly distributed when passing through the fuel flow equalizerin the combustor.

In large combustion volumes, large flames may be under relatively highpressure and may behave rapidly, making it difficult to pull down theflames. The fuel flow equalizer may help in stabilizing powered flamesand provide suitable aerodynamic fuel equalization.

According to other embodiments, in addition to improving flame stabilityby reducing fuel flow velocity with the fuel flow equalizer, flamestability may be further enhanced or improved by adding a flameanchoring apparatus (e.g., an electrically charged and electricallyconductive anchoring apparatus), which may be positioned downstream fromthe fuel flow equalizer. As such, both the fuel flow equalizer and theanchoring apparatus may lead to firm attachment or coupling of the flameto the anchoring apparatus. The fuel flow equalizer may be configured ina manner that facilitates positioning the flame above the anchoringapparatus (i.e., downstream) or below the anchoring apparatus (i.e.,upstream from), as may be required or suitable for a particularapplication.

Embodiments disclosed herein may facilitate rapid mixing of fuel and airresulting in a compact combustion zone. Additionally or alternatively,embodiments disclosed herein may facilitate flame stabilization and fuelvelocity control that may allow slowing down the velocity of the flameto the extent that the flame can or does not anchor to the fuel flowequalizer but instead anchors to the anchoring apparatus. The fuel flowequalizer may be a mechanical device for spreading and enlarging flamesaerodynamically.

From an aerodynamic point of view, a fuel flow equalizer may overcomelimitations of known combustion system which can present difficultiesholding flames away from electrodes comprising the anchoring apparatusat very high BTU levels. The embodiments disclosed herein may minimizeemissions by aerodynamically anchoring the flame.

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings, whichare not to scale or to proportion, similar symbols typically identifysimilar components, unless context dictates otherwise. The illustrativeembodiments described in the detailed description, drawings and claims,are not meant to be limiting. Other embodiments may be used and/or andother changes may be made without departing from the spirit or scope ofthe present disclosure.

FIGS. 1A and 1B illustrate operation of a burner without a fuel flowequalizer. More specifically, FIG. 1A illustrates an example of fueldistribution as fuel 102 exists a burner nozzle 104. In someembodiments, the burner nozzle 104 may inject the fuel 102 into acombustion space 106. Generally, the burner nozzle 104 injects the fuel102 downstream therefrom, as indicated by the arrows.

The combustion space 106 may be an open or at least partially closedchamber, which may include one or more structures (e.g., chamber walls)that may at least partially enclose the fuel 102 and the flame combustedfrom the fuel 102 therein. Hence, the combustion space 106 may be formedor defined by one or more chamber walls, which may collectively form thecombustion space. In some embodiments, at least a portion of the burnernozzle 104 also may be included inside the combustion space.Alternatively, however, the combustion space may be at least mostly open(i.e., the fuel 102 may be injected into a natural, outside environmentand may combust therein).

The fuel 102 may be ignited and/or combusted downstream from the burnernozzle 104 to form a flame. Hence, in an embodiment, the fuel 102 may bemixed with an oxidizer (e.g., air, oxygen, etc.), which may promoteand/or facilitate combustion of the fuel 102. In some embodiments, thefuel 102 may be premixed with the oxidizer and may exit the burnernozzle 104 together therewith. Alternatively, the fuel 102 may at leastpartially mix with the oxidizer inside the combustion space 106.

In some instances, without the fuel flow equalizer, a velocity of thefuel 102 within the combustion space varies with distance from theburner nozzle 104. More specifically, near the burner nozzle 104 thefuel 102 has higher velocity than farther away from the burner nozzle104. In other words, as the fuel 102 flows downstream and away from theburner nozzle 104, the velocity of the fuel 102 decreases.

In some instances, velocity zones may be defined as velocity zones V₁,V₂, and V₃. As noted above, velocity of the fuel 102 in the V₁ zone maybe higher than in V₂ and V₃. Likewise, velocity of the fuel 102 in theV₂ zone may be less than in the V₁ zone but greater than in the V3 zone(i.e., in some embodiments, V₁>V₂>V₃). It should be also appreciatedthat velocity of the fuel 102 may vary within any of the V₁, V₂, and V₃zone (e.g., velocity of the fuel 102 that is closer to the downstreamend of the zone may be lower than at the upstream end thereof). In someexamples, velocities of the fuel 102 in the V₁ zone may be near sonic(i.e., subsonic) or supersonic.

FIG. 1B illustrates an example of a flame formed during combustion ofthe fuel and oxidizer mixture shown in FIG. 1A. In particular, FIG. 1Billustrates a flame 108 combusted in the combustion space 106, and thebehavior of the flame 108 according to the velocity distribution of thefuel 102 (shown in FIG. 1A). The fuel flow velocities near the burnernozzle 104 may be high subsonic, making control of the flame 108 moredifficult in the areas closer to the burner nozzle 104.

Generally, an ignition source or an igniter may ignite the fuel andoxidizer mixture to initiate combustion and produce the flame 108. Insome embodiments, the ignition source may be a pilot light.Alternatively, the ignition source may include a spark igniter (e.g., apiezo igniter) may ignite the fuel and oxidizer mixture to produce theflame 108. In any event, the ignition source may include any number ofsuitable mechanisms and devices that may ignite the fuel and oxidizermixture to produce the flame 108.

In some instances, the flame 108 may be easier to control at lowervelocities of flow. In the absence of a fuel flow equalizer, differentfactors may affect combustion and stability of the flame 108. Suchfactors include, but are not limited to, heat requirement variations,weather, and componentry wear or damage, among others. In someinstances, combustion of the fuel flowing at high speeds may produceincreased emissions of pollutants (e.g., NOx, CO, HC, etc.), flash back,poor heat transfer, reduced component life, unplanned shutdowns,potential system damage, etc.

The flame 108 may include a variety of charged and uncharged particlesand molecules. The volume of charged particles may include electrons110, positive ions 112, negative ions, positively and negatively chargedparticles, positively and negatively charged fuel vapor, and positivelyand negatively charged combustion products. Locations, quantities orvolume of various charged particles within the flame 108 may vary fromone embodiment to the next as well as during the combustion process.

In addition to or in lieu of the charged particles, the flame 108 mayinclude uncharged combustion, unburned fuel and oxidizer, such as air.Moreover, generally, the charged particles have been viewed astransient. Hence, the charged particles typically have not beenmanipulated. In some embodiments, reducing and/or controlling thevelocity of the fuel flow may lead to a more stable combustion andflame.

FIGS. 2A and 2B illustrate a velocity profile of a fuel flow controlledand/or regulated by a fuel flow equalizer 202 and combustion of thefuel, respectively. More specifically, as illustrated in FIG. 2A, thefuel flow equalizer 202 may be placed downstream from the burner nozzle104, such that the flow of the fuel 102 may interact with the fuel flowequalizer 202. As noted above and as described in further detail below,the fuel flow equalizer 202 may interact with the flow of the fuel 102in a manner that produces a suitable or selected flow velocity of thefuel 102 downstream from the fuel flow equalizer 202.

In one or more embodiments, the fuel flow equalizer 202 may be placeddownstream from a velocity zone V_(1a), which may have the same orsimilar flow velocities and/or velocity distribution as the V₁ zone(FIGS. 1A and 1B). For example, the fuel flow equalizer 202 may beplaced in a velocity zone V_(2a). Hence, a portion of the flow of fuel102 within the V_(2a) zone may have a different velocity profile thananother portion of the flow of the fuel 102. In particular, the portionof the flow of the fuel 102 upstream from the fuel flow equalizer 202may have higher velocity than the portion of the flow of the fuel 102downstream from the fuel flow equalizer 202. It should be alsoappreciated that zones V_(1a), V_(2a), V_(3a) are chosen for descriptivepurposes only and provide a distance and flow velocity referencerelative to the burner nozzle 104. Thus, the flow of the fuel 102 mayhave any number of velocity zones and the fuel flow equalizer 202 may bepositioned within one or more of such zones.

In some embodiments, the fuel flow equalizer 202 may be generallyplanar. In other words, at least one side of the fuel flow equalizer 202may be approximately flat. Moreover, in some embodiments, the fuel flowequalizer 202 may be positioned approximately perpendicular to theburner nozzle 104, for instance, such that the planar or flat side ofthe fuel flow equalizer 202 is substantially perpendicular to animaginary centerline that passes through the burner nozzle 104. Itshould be appreciated, however, that the fuel flow equalizer 202 alsomay have non-planar configurations. Furthermore, the fuel flow equalizer202 may be oriented at any number of suitable orientations relative tothe burner nozzle 104 and/or to the flow of the fuel 102, andorientations may vary from one embodiment to the next.

The fuel flow equalizer 202 may be supported downstream from the burnernozzle 104 in any number of ways. For example, a stand, multiple posts,or other elements and/or components may secure the fuel flow equalizer202 to a support surface near the burner nozzle 104 (e.g., to a floor ofthe combustion space). Additionally or alternatively, the fuel flowequalizer 202 may be secured to one or more walls that may form ordefine the combustion space. In any event, the fuel flow equalizer 202may be positioned at a suitable location and orientation downstream fromthe burner nozzle 104.

In an embodiment, the flow of the fuel 102 may have an approximatelyuniform distribution after passing through and exiting the fuel flowequalizer 202. Also, the maximum velocity of the flow of fuel 102 may bereduced immediately after or near the burner nozzle 104. Therefore, thevelocity of the flow of fuel 102 in zones V_(2a) and V_(3a) may be lowerthan flow velocity in the zones V₂ and V₃ (FIGS. 1A and 1B),respectively.

FIG. 2B illustrates combustion of the fuel that passed through the fuelflow equalizer 202 according to an embodiment. The fuel that exits theburner nozzle 104 is ignited, and the combusted fuel forms a flame 208.In particular, reduced and/or equalized fuel flow velocities (afterpassing through the fuel flow equalizer 202) may produce a wider andshorter flame 208 (as compared with the flame 108 (FIG. 1B) producedwithout the fuel flow equalizer 202. As such, the flame 208 may havegreater stability than the flame 108 (FIG. 1B).

Generally, the fuel flow equalizer 202 may be made of any suitablematerials, which may include heat and/or corrosion resistant metallicmaterials. For instance, the fuel may burn or combust at temperatures inexcess of about 2,800° F. Accordingly, in some embodiments, the fuelflow equalizer 202 may include materials that may withstand temperaturesof at least about 2,800° F. More specifically, embodiments may includerefractory metals, such as molybdenum, tungsten, niobium, tantalum,rhenium, alloys of the foregoing, ceramic materials, combinationsthereof, or other suitable materials.

It should be also appreciated that the fuel flow equalizer 202 mayinclude other metals and/or materials. For example, the fuel flowequalizer 202 may include graphite. The fuel flow equalizer 202 also mayinclude sintered materials, such as sintered refractory metal materials.The sintered refractory metal materials may exhibit a meltingtemperature or temperature range (e.g., a solidus temperature or aliquidus temperature) of about 1600° C., about 1800° C., about 2000° C.,about 2200° C., 2400° C., 2600° C., 2800° C., 3000° C., 3000° C., orabout 3200° C. In other embodiments, the sintered refractory metalmaterials may exhibit a melting temperature or temperature range betweenabout 1600° C. and about 3500° C.; about 1800° C. and about 3200° C.;about 2000° C. and about 3000° C.; or about 2300° C. and about 2800° C.Also, the sintered refractory metal materials may exhibit higher orlower melting temperatures or temperature ranges.

As described below in more detail, the fuel flow equalizer 202 may havevarious shapes and sizes, which may vary from one embodiment to thenext. The particular shape and size of the fuel flow equalizer 202 maydepend on the shape and/or size of the combustion space, burner nozzle,position and/or orientation of the fuel flow equalizer 202 relativenozzle and/or within the fuel flow, among others. In some embodiments,the fuel flow equalizer 202 may include a mesh, a honeycomb, or apattern of alternating opens spaces or openings and barrier elements. Asdescribed below, the pattern of openings in the fuel flow equalizer 202may vary from one embodiment to another.

Also, in some embodiment, a single fuel flow equalizer 202 may be placeddownstream from the burner nozzle 104. Alternatively, a plurality offuel flow equalizers may be placed downstream from the burner nozzle104. In one or more embodiments, the plurality of fuel flow equalizersthat may be placed downstream from the burner nozzle 104 may have thesame orientation and/or the same mesh or patterns as one another (e.g.,the opening in the mesh of the multiple fuel flow equalizers may beapproximate aligned with one another). For example, the plurality offuel flow equalizers may be arranged in series with each other. Inadditional or alternative embodiments, at least some of the fuel flowequalizers may be oriented in a manner that misaligns openings in themesh of one fuel flow equalizer with another fuel flow equalizer.Furthermore, one, some, or all of the fuel flow equalizers may be thesame. Alternatively, at least one fuel flow equalizer may be differentfrom at least one other fuel flow equalizer.

In an embodiment illustrated in FIG. 3A the fuel flow equalizer 202 amay have an approximately circular or cylindrical peripheral shape.Except as otherwise described herein, the fuel flow equalizer 202 a andits materials, elements, and components may be similar to or the same asthe fuel flow equalizer 202 (FIGS. 2A and 2B) and its correspondingmaterials, elements, and components. In an embodiment, the fuel flowequalizer 202 a may include a plurality of rib members 204 a that mayform a mesh that includes multiple flow openings 206 a.

In some embodiments, the rib members 204 a may be interconnected (i.e.,connected or coupled together) to form the flow openings 206 a. Forinstance, at least some of the rib members may be mechanically connectedtogether (e.g., riveted, press-fit, folded one over another, may includeslits that slide over portions of the rib members 204 a, etc.).Alternatively, the rib members 204 a may be bonded together orintegrated (i.e., integrally formed) with one another. Examples ofsuitable bonding may include brazing, welding (including spot welding),etc. In any event, the fuel and/or oxidizer may pass through the flowopenings 206 a, as the fuel moves downstream from the nozzle. Moreover,as described above, the flow velocity of the fuel may be reduced and maybecome more uniform after the fuel passes through the fuel flowequalizer 202 a.

The rib members 204 a may have a suitable thickness and height.Furthermore, in some examples, the height of the rib members 204 a maydefine the thickness of the fuel flow equalizer 202 a. Likewise, theheight of the rib members 204 a may define a length of the flow openings206 a (i.e., the length of the path for the fuel flow between entranceinto the flow openings 206 a and exit therefrom). Accordingly, in someembodiments, to increase the length of the flow openings 206 a, thethickness of the rib members 204 may be increased. Conversely, todecrease the length of the flow openings 206 a, the thickness of the ribmembers 204 a may be decreased.

In some embodiments, the perimeter or periphery of the fuel flowequalizer 202 a may be unbound or unenclosed and may be formed by therib members 204 a. For example, at least some ends or portions of therib members 204 a may be exposed at and/or about the periphery of thefuel flow equalizer 202 a. Alternatively, the periphery of the fuel flowequalizer 202 a may be enclosed (e.g., by a band), such that the ends ofthe rib members 204 a are not exposed about the periphery of the fuelflow equalizer 202 a. For example, the fuel flow equalizer 202 a mayhave a relatively smooth surface that defines the periphery thereof.

In additional or alternative embodiments, the fuel flow equalizer mayhave non-circular or non-cylindrical shapes. FIG. 3B, for example,illustrates a fuel flow equalizer 202 b that has an approximatelyrectangular shape according to an embodiment. Except as otherwisedescribed herein, the fuel flow equalizer 202 b and its materials,elements, and components may be similar to or the same as any of thefuel flow equalizers 202, 202 a (FIGS. 2A-3A) and their correspondingmaterials, elements, and components. For example, the fuel flowequalizer 202 b may include a mesh or pattern of openings and ribmembers that may be similar to or the same as the pattern of the fuelflow equalizer 202 a (FIG. 3A).

In some embodiments, the rectangular shape of the fuel flow equalizer202 b may facilitate coverage of multiple burner nozzles, which may bedisposed along the length of the fuel flow equalizer 202 b. In otherwords, the fuel from multiple burner nozzles may flow downstream througha single fuel flow equalizer 202 b. It should be appreciated, however,that any of the fuel flow equalizers described herein may be positioneddownstream from a single or multiple burner nozzles to equalize fueland/or oxidizer flow therefrom.

Furthermore, additional or alternative embodiments include a square fuelflow equalizer 202 c, shown in FIG. 3C. Except as otherwise describedherein, the fuel flow equalizer 202 c and its materials, elements, andcomponents may be similar to or the same as any of the fuel flowequalizers 202, 202 a, 202 b (FIGS. 2A-3B) and their correspondingmaterials, elements, and components. Other embodiments may include fuelflow equalizer that may have a non-rectangular or non-square shape(e.g., polygonal, hexagonal, irregular shaped, etc.). In any event, oneor more fuel flow equalizers may be placed downstream from one or moreburner nozzles, and the fuel flow equalizers may have suitable shapesand sizes to equalize fuel flow and/or reduce fuel flow velocity.

As mentioned above, the fuel flow equalizer may have any number ofsuitable patterns of openings and rib members that separate the openingsone from another. For example, FIG. 3D illustrates a fuel flow equalizer202 d that includes a suitable pattern according to an embodiment.Except as otherwise described herein, the fuel flow equalizer 202 d andits materials, elements, and components may be similar to or the same asany of the fuel flow equalizers 202, 202 a, 202 b, 202 c (FIGS. 2A-3C)and their corresponding materials, elements, and components.

As described above, in some embodiments, the fuel flow equalizer 202 dmay include a band 208 d that may at least partially surround the meshor grid pattern formed by rib members 204 d, 204 d′ and flow openings206 d, 206 d′. More specifically, the band 208 d may enclose otherwiseunbound ends of the rib members 204 d and/or rib members 204 d′. Theband 208 d may form or define a peripheral surface of the fuel flowequalizer 202 d (e.g., the peripheral surface may be substantiallycontinuous, smooth, ribbed, etc., as may be formed by the surface of theband). Generally, the band 208 d may have the same approximateperipheral shape as the shape formed by unbounded rib members 204 dand/or rib members 204 d′. Alternatively, the shape formed by the band208 d may be different from the shape formed by the unbounded ribmembers 204 d and/or rib members 204 d′ (e.g., the 208 d may have anon-uniform thickness about the periphery thereof).

The band 208 d also may provide additional structural support and/orrigidity to the rib members 204 d, 204 d′. For instance, the band 208 dmay facilitate securing the fuel flow equalizer 202 d downstream fromthe nozzle. In some embodiments, the band 208 d may include similar orthe same material as the rib members 204 d, 204 d′. In additional oralternative embodiments, material of the band 208 d may be differentfrom the material of the rib members 204 d, 204 d′. In any case, theband 208 may have sufficient rigidity and/or heat resistance.

In some embodiments, the fuel flow equalizer 202 d may include a meshformed by multiple rib members 204 d and rib members 204 d′, which maydefine multiple flow openings 206 d, 206 d′. For example, the flowopenings 206 d may have an elongated hexagonal shape. In particular, inone embodiment, four angled sides of the hexagonal opening flow openings206 d may be longer than two opposing sides of the flow openings 206 d.In other words, four of the rib members 204 d that define the flowopenings 206 d may be long rib members 204 d, while two sides of theflow openings 206 d may be defined by short rib members 204 d′.

Furthermore, in at least one embodiment, the flow openings 206 d′ mayhave a parallelogram shape. For example, two sides of the flow openings206 d′ may be defined by long rib members 204 d and two sides may bedefined by short rib members 204 d′. Additionally, at least some of theflow openings 206 d′ may share one or more of the rib members 204 dand/or rib members 204 d′ with the flow openings 206 d. For instance,the same rib members 204 d that define two long sides of the flowopenings 206 d′ may partially define long sides of two flow openings 206d, which may be adjacent to and on opposite sides of the flow openings206 d′.

Similarly, the same rib members 204 d′ that define the two short sidesof the flow openings 206 d′ may partially define short sides of two flowopenings 206 d, which may be adjacent to and on opposite sides of theflow openings 206 d′. Hence, in some embodiments, the flow openings 206d′ may be adjacent to one, two, three, or four of the flow openings 206d (e.g., the flow opening 206 d′ may be surrounded by four flow openings206 d on all sides of the flow opening 206 d′). Moreover, it should beappreciated that the area of the flow openings 206 d may be greater thanthe area of the flow openings 206 d′.

Also, the flow openings may be defined by any number of rib members,which may have any suitable length as well as length ratio one toanother (e.g., rectangular flow openings may have any suitable length towidth ratio). In some embodiments, the flow openings may be hexagonalwith all sides having approximately the same length. Accordingly,embodiments may include flow openings that may have any suitablepolygonal shape. Moreover, embodiments also may include openings thathave circular, semicircular, or irregular shapes. FIG. 3E, for example,illustrates a fuel flow equalizer 202 e that has approximately oval flowopenings 206 e defined by one or more rib members 204 e according to anembodiment. Except as otherwise described herein, the fuel flowequalizer 202 e and its materials, elements, and components may besimilar to or the same as any of the fuel flow equalizers 202, 202 a,202 b, 202 c, 202 d (FIGS. 2A-3D) and their corresponding materials,elements, and components.

For example, the oval flow openings 206 e may be placed adjacent oneanother in a manner that defines additional openings flow openings 206e′, which may be located between four flow openings 206 e that surroundthe flow openings 206 e′. In other words, portions of the rib members204 e that define four flow openings 206 e also may define the flowopenings 206 e′ that may be located between the four flow openings 206e. In additional or alternative embodiments, as mentioned above, theflow openings may be circular. Similarly, however, the rib members thatdefine circular openings may define additional openings between thecircular openings.

Embodiments also may include rectangular openings that may be alignedwith one another and form multiple rows and/or columns. FIG. 3F, forinstance, illustrates a fuel flow equalizer 202 f that includerectangular flow openings 206 f formed by multiple rib members 204 faccording to an embodiment. Except as otherwise described herein, thefuel flow equalizer 202 f and its materials, elements, and componentsmay be similar to or the same as any of the fuel flow equalizers 202,202 a, 202 b, 202 c, 202 d, 202 e (FIGS. 2A-3E) and their correspondingmaterials, elements, and components.

Also, the rib members 204 f may overlap one another. For example, therib members 204 f may span or extend between outermost edges of the fuelflow equalizer 202 f. Moreover, the rib members 204 f may include slitsthat may pass through a portion of the height of the rib members 204 f(e.g., half-way through the height). Such slits on the rib members 204f, which oriented perpendicularly to one another, may be aligned in amanner that a slit of one rib member 204 f enters into the slit inanother rib member 204 f and vice versa. In other words, the rib members204 f may overlap and connect to one another via multiple slits therein.

It should be appreciated that In addition, the fuel flow equalizer mayinclude other suitable patterns of flow openings and rib members and thepatterns disclosed herein should not be considered as an exhaustive listnor limiting the present disclosure. In general, the fuel flow equalizerpatterns can exhibit dimensions according to desired fuel flow velocitydistribution characteristics and system design.

As described above, the fuel and/or flame also may encounter and may beinfluenced by a flame anchoring apparatus, which may control the shapeand/or position of the flame. For example, FIG. 4 shows a combustionsystem 300 that may include a flame anchoring apparatus 302 locateddownstream from the burner nozzle 104 according to an embodiment. Exceptas otherwise described herein, the fuel flow equalizer 202 g and itsmaterials, elements, and components may be similar to or the same as anyof the fuel flow equalizers 202, 202 a, 202 b, 202 c, 202 d, 202 e, 202f (FIGS. 2A-3F) and their corresponding materials, elements, andcomponents.

In some embodiments, the flame anchoring apparatus 302 may be locateddownstream (or after) a fuel flow equalizer 202 g. Accordingly, asubstantially equalized fuel flow and/or a flame formed therefrom mayencounter the flame anchoring apparatus 302. In some embodiments, theflame anchoring apparatus 302 may be configured as an electricallyconductive bluff body or an electrically conductive toric body (e.g., anannulus or other type of body having a passageway through which fuelflow from passing through the fuel flow equalizer 202 g may flow).

In some embodiments, the fuel flow equalizer 202 g and the flameanchoring apparatus 302 may be integrated (e.g., the fuel flow equalizer202 g may be configured to anchor the flame thereto and/or may beintegrally formed together with the flame anchoring apparatus 302).Additionally or alternatively, the fuel flow equalizer 202 g and flameanchoring apparatus 302 may be connected or coupled to one another. Inany event, in at least one embodiment, the flame anchoring apparatus 302may receive equalized fuel flow or the flame formed from such flow. Forinstance, the fuel and/or oxidizer may pass through and exit the fuelflow equalizer 202 g before encountering the flame anchoring apparatus302.

Generally, the flame anchoring apparatus 302 may control shape and/orposition of a charged flame 308. For example, the charged flame 308 maybe charged by injecting charge into the fuel and/or the flame. Byinjecting charge with a charger 310, the fuel, flame, or combinationsthereof acquires a net electrical charge (e.g., a net positive ornegative charge). In an embodiment, the charger 310 may include a coronaelectrode (e.g., a sharpened electrode or saw blade) configured togenerate ions that are injected into the fuel, flame, or combinationsthereof to impart the net electrical charge. A voltage power supply 304(e.g., a high voltage power supply) biases the charger 310 to causecharges to be emitted from the charger 310. The flame anchoringapparatus 302 is also electrically coupled to the voltage power supply304 and biases the flame anchoring apparatus 302 oppositely to the biasof the charged flame 308 to electrodynamically attract the charged flame308 to the flame anchoring apparatus 302. For example, application ofthe bias to the flame anchoring apparatus 302 may control the positionand/or shape of the charged flame 308. More specifically, the voltagepower supply 304 and the anchoring apparatus 302 may generate anelectric field near one or more surfaces or sides of the flame anchoringapparatus 302, which may attract, couple, and/or anchor the chargedflame 308 to at least one side of the anchoring apparatus 302.

The fuel flow equalizer 202 g may assist on maintaining the chargedflame 308 attached to the flame anchoring apparatus 302. The chargedflame 308 may tend to move around the desired position above or belowthe flame anchoring apparatus 302, thus being more stably anchored (ascompared to the combustion without the flame anchoring apparatus 302).The fuel flow equalizer 202 g may be positioned between the burnernozzle 104 and the flame anchoring apparatus 302 to allow a more uniformfuel flow velocity distribution that may contribute to more efficientflame stabilization around the flame anchoring apparatus 302.

Generally, the flame anchoring apparatus 302 may include any suitablematerial that may be electrically conductive. As such, the voltage powersupply 304 and the flame anchoring apparatus 302 may produce an electricfield near the flame anchoring apparatus 302, which may be controlled bythe voltage power supply 304 in a manner that controls the charged flame308. Moreover, in some embodiments, the combustion system 300 mayinclude one or more sensors, which may determine direction of currentflow to or from the flame anchoring apparatus 302. Accordingly, thevoltage power supply 304 and the sensors may provide spark managementand detection in of flashback event and/or other operational failures.

As noted above, the fuel flow equalizer 202 g may equalize and/or reducethe fuel flow velocity. Accordingly, in some embodiments, the fuel flowequalizer 202 g can enable or facilitate the flame anchoring apparatus302 to operate at a higher rate of fuel throughput. In other words, thefuel flow equalizer 202 g may increase operating efficiency of thecombustion system 300 (as compared with an electrodynamic flame controlsystem that does not include the fuel flow equalizer 202 g).

While various aspects and embodiments have been disclosed, other aspectsand embodiments may be contemplated. The various aspects and embodimentsdisclosed here are for purposes of illustration and are not intended tobe limiting, with the true scope and spirit being indicated by thefollowing claims.

What is claimed is:
 1. A combustion system, comprising: at least oneburner nozzle configured to discharge fuel into a combustion space sizedand configured to at least partially contain a flame produced duringcombustion of the fuel and an oxidizer; at least one fuel flow equalizerpositioned downstream from the at least one burner nozzle, the fuel flowequalizer including a plurality of openings sized and configured toallow the fuel to pass therethrough; a flame anchoring apparatuspositioned downstream from the at least one fuel flow equalizer; and avoltage power supply electrically coupled to the flame anchoringapparatus, the voltage power supply being configured to bias the flameanchoring apparatus so that the flame is attracted to the flameanchoring apparatus.
 2. The combustion system of claim 1, wherein theflame anchoring apparatus include an electrically bluff body.
 3. Thecombustion system of claim 1, wherein the flame anchoring apparatus andthe at least one fuel flow equalizer are integral with each other. 4.The combustion system of claim 1, wherein some openings of the pluralityof openings are larger than other openings of the plurality of openings.5. The combustion system of claim 1, wherein the plurality of openingsincludes first openings and second openings, and the first openings haveone or more of a different shape or size than the second openings. 6.The combustion system of claim 1, wherein at least some openings of theplurality of openings of the at least one fuel flow equalizer have anapproximately hexagonal shape.
 7. The combustion system of claim 1,wherein at least some openings of the plurality of openings of the atleast one fuel flow equalizer have one or more of an approximatelyrectangular shape, a parallelogram shape, a round shape, or an ovalshape.
 8. The combustion system of claim 1, wherein the voltage powersupply and the flame anchoring apparatus produce an electric field nearat least one surface of the flame anchoring apparatus when the flameanchoring apparatus is biased by the voltage power supply.
 9. A methodfor stabilizing a flame within a combustion space, the methodcomprising: discharging fuel from at least one nozzle into a combustionspace; passing the fuel through at least one fuel flow equalizerstructure positioned downstream from the nozzle; igniting the fuel andan oxidizer to produce a flame; applying an electrical potential to aflame anchoring apparatus effective to anchor the flame to the flameanchoring apparatus.
 10. The method of claim 9, wherein the at least onefuel flow equalizer includes a structure having a plurality of openingsseparated by a plurality of rib members.
 11. The method of claim 10,wherein the at least one fuel flow equalizer is oriented generallyperpendicular to the nozzle.
 12. The method of claim 9, wherein theflame anchoring apparatus includes an electrically conductive bluffbody.
 13. The method of claim 9, wherein the flame anchoring apparatusis positioned in the stream of flow of the mixture of fuel and air. 14.The method of claim 9, wherein passing the fuel through the at least onefuel flow equalizer structure positioned downstream from the at leastone nozzle occurs before applying the electrical potential to the flameanchoring apparatus.
 15. The method of claim 9, wherein passing the fuelthrough the at least one fuel flow equalizer structure positioneddownstream from the at least one nozzle includes: passing at least someof the fuel through first openings in the at least one fuel flowequalizer; and passing at least some of the fuel through second openingsin the at least one fuel flow equalizer, wherein the first openings haveone or more of a different size or different shape than the secondopenings.
 16. A flame control system, comprising: at least one burnernozzle configured to discharge fuel into a combustion space sized andconfigured to at least partially contain a flame produced duringcombustion of the fuel and an oxidizer; at least one fuel flow equalizerdisposed downstream from the burner nozzle, the fuel flow equalizerincluding a plurality of openings sized and configured to allow the fuelto pass therethrough; a flame anchoring apparatus positioned downstreamfrom the at least one fuel flow equalizer so that the fuel exiting theat least one fuel flow equalizer encounters the flame anchoringapparatus; a charger configured to charge at least one of the flame orthe fuel to form a charged flame; and a voltage power supplyelectrically coupled to the flame anchoring apparatus and configured toapply an electrical potential thereto that attracts the charged flame tothe flame anchoring apparatus.
 17. The flame control system of claim 16,wherein the flame anchoring apparatus includes an electricallyconductive body.
 18. The flame control system of claim 16, wherein theat least one fuel flow equalizer is generally perpendicular to theburner nozzle.
 19. The flame control system of claim 16, wherein theplurality of openings are defined by a plurality of interconnected ribmembers.
 20. The flame control system of claim 19 wherein the ribmembers include one or more of molybdenum, tungsten, niobium, tantalum,rhenium, alloys of thereof, or graphite.